Air conditioning system



' March 22, 1938'.

D. W. M LENEGAN AIR CONDITIONING SYSTEM Original Filed May 5, 1936.Patented Mar. 22, 1938 7 2,112,039 AIR CONDITIONING SYSTEM David W.McLenegan, Caldwell, N. 1., assignor to General Electric Company,a'corporation of New York Application May 5. 1936, Serial No. 77,985Renewed December 11, 1937 l 9 Claims.

My invention relates to air conditioning systems for cooling anddehumidifying the air within auditoriums, rooms and other enclosures.

It is an object of my invention to provide a system for cooling anddehumidifying the air Within an enclosure including a cooling coil and aplurality of valves for controlling the admission of cooling medium tothe coil and having an arrangement for selecting any one of theadjustable dampers i211. A filter i6 is provided valves dependent uponthe desired effective cooling surface of the coil as determined by thetemperature and humidity of the air in the enclosure.

. Further objects and advantages of my invention willbecome apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to theaccompanying drawing in which Fig. 1 shows diagrammatically an airconditioning system embodying my invention, and Fig. 2 shows a modifiedarrangement of the controlling valves shown in Fig. 1.

Referring now to the drawing, in Fig. 1 I have shown an air conditioningsystem comprising a casing I0 arranged to receive fresh air through aduct H and air from the room to be conditioned through a duct I2 whichpasses through a wall l3 o'fthe room. The fresh air and the room air aredrawn into the casing H) by operation of a fan It, arranged at thedischarge side of the casing, and the conditioned air is .conducted tothe room through a duct I5 passing through'the wall iii. The quantity offresh air utilized is controlled by adjustable dampers Ila, and thequantity of room air is controlled by in the casing ID to remove dustand other impurities from the air, and the air is cooled by passingthrough a cooling element ll arranged in the casing and comprising asinuous coil I8 having a plurality of turns extending entirely acrossthe casing in the path of the air. The

coil I8 is preferably of the type having a plurality of fins providing alarge surface area in the path of the air passing through the coolingelement. 'The coil l8is connected in the circuit of a mechanicalrefrigerating machine including a I compressor l9 driven by a motor 20,a condenser 2F and a liquid'receiver 22. Gaseous refrigerant iscompressed in the compressor l9 and is discharged into the condenser Mwhere it is cooled and liquefied by air circulated thereover by a fan.

. 23. The fan 23 isdriven by a motor 28 connected across the motor 20.The condensed refrigerant flows into the liquid receiver 22 and issupplied to the coil It under normal conditions by operation of athermostatic expansion valve 25, provided with a thermostatic bulb 26arranged in contact with the suction side of the coil H8. The valve is,therefore, operated in response to thetemperature of the vaporizedrefrigerant withdrawn from the coil it. The refrigerant is preferablyadmitted to the coil l8 so that it flows through the banks ma, I 8b, andI80 of the coil in succession in the opposite direction from that of theflow of air through the duct It. The air thus passes from the least coldto the coldest portion of the coil. Refrigerant vapor is withdrawn fromthe coil it through a conduit 27 and is returned to the compressor.

The refrigerating machine is controlled under normal conditions by athermostat 28 having a relay 28a. Under conditions of excess humidity ofthe air in the enclosure the refrigerating machine may be controlled bya room humidostat 29 having a relay 29a. The thermostat 28 is arrangedto control a switch 30 in the power supply line of the motor 20. Shouldthe humidity of the air in the room he abnormally high it is possiblethat the temperature of the air may be reduced sufliciently to satisfythe thermostat 28 before the humidity has been reduced the desiredamount to provide maximum comfort for the occupants in the room. In suchcases it is desirable further to dehumidify the air, but any substantialdecrease of the temperature of the air in the room-must be avoided inorder to maintain a comfortable temperature for the occupants of theroom. However, it may be permissible to continue the cooling action at areduced rate in order that the humidity'may be reduced further.

' In most air conditioned spaces some of the heat which must be removedby the air conditioning system originates within the room itself. Forexample, occupants, electric lights, motors and other heat producingappliances and also the suns rays entering through the windows, allgenerate heat within the room. It is necessary that the heat from suchinternal sources be removed from the room before any reduction of thetemperature in the room below that of the outdoor air can beaccomplished. It is evident, therefore, that part of the capacity of thecooling system must be devoted to the removal of heat from theseinternal sources. In air conditioning systems in which the internal heatof the space to be conditioned must be removed, a small portion ofcooled air may be circulated continuously without reducing the totalsensible heat of the air in the space to be conditioned. It is possiblein such systems to produce a substantial amount of dehumidification withonly sufficient sensible cooling to oflset the effect of the internalheat sources in the room so that dehu-- midificationmay be accomplishedwithout reduction of the dry bulb temperature of the air in the room.

If the thermostat 28 be satisfied due to the reduction of thetemperature of the air of the room to a predetermined'low value beforethe humidity has been reduced sufliciently to satisfy the humidostat 29,the humidostat will take over the control of the motor 26. The motorwill continue to operate under the control of the humidostat until thehumidity has been reduced the desired amount or until a minimumpermissible temperature has been reached as determined by a lowtemperature limit thermostat 3l.

When the motor is under the control of the humidostat the supply ofrefrigerant to the coil is reduced and, consequently, anincreasedpercentage of the total coil length is filled with superheatedrefrigerant gas. With the flow of refrigerant restricted, the balance ofheat transfer capacity between the coil and the compressor is changed sothat a lower refrigerant pressure is maintained in the coil. At thislower pressure the saturation temperature of the refrigerant is lowerand the surface temperature of the coil is, therefore, lower in thatportion of the coil in which the gas is not superheated. Thedehumidification accomplished by this cold portion of the coil isincreased as compared with the dehumidification during the normaloperation of that portion, but the total sensible heat removed from theair by the coil is reduced.

The above described system for effecting a control of temperature andhumidity by modifying the operation of the refrigerant supplycontrolling device in accordance with the humidity of the air in anenclosure, is not my invention, but is the invention of Edward W.Roessler and is described and claimed in his copending application,Serial No. 77,949; filed May 5, 1936, and assigned to the GeneralElectric Company, assignee of my present invention.

When it is desired to operate the air conditioning system illustrated inFig. 1, electric energy is supplied to lines 32 and 33. This energizes atransformer 34 having a primary winding 35 and a secondary winding 36.If the temperature of the air in the room rises to a predetermined valuea bimetallic strip 31 of the thermostat 28 engages a contact 38 andcloses a circuit from one side of the primary 36 through a connection39, the strip 31 and a connection 40 to a coil 4| of relay 28a andthence back to the other side of the primary 36 through a connection 42and a line. 43. The coil 4| will thereby be energized and will pick upan armature 44 of the relay 28a, raising arms 45 and 46 of the relayinto engagement with contacts 41 and 48, respectively, and breakingengagement between the arm 46 and a contact 49. The raising of arm 46closes a-holding circuit for the coil 4| through connections 50 and5l.thereby' maintaining the coil energized even though the strip 31should move out of engagement with the contact 38. The raising of thearm' 45 closes a circuit of a coil 52 of the switch 30 from line 32anaoao through a connection 53, the arm 45, a line 54! to the coil andthence back to line 33 through a connection 55. The energization of coil52 picks up an armature 56 of switch 30 thereby closing the switch andconnecting motor leads 5'! and 58 to lines 32 and 33, respectively. Thisstarts the motor 29 and thereby operates the compressor l to supplyrefrigerant to the coil l8, and also starts the condenser fan motor 2 1.The operation of the motors will continue until a predetermined lowtemperature of the air in the room has been reached, when the bimetallicstrip 37! will engage a contact 59; this short-circuits the relay coilii through connections. 42 and 66, strip 37 and connection 46 therebydeenergizing the coil and causing relay 28a. to drop out and break thecircuit of the coil 52 to open the switch 38. The operation of thecompressor 59 and fan motor 2A is thereby stopped and the supply ofrefrigerant to the coil l8 discontinued.

When the air conditioning system is operating as just described thesupply of liquid refrigerant is controlled by the valve 25 whichmaintains a minimum temperature of the refrigerant withdrawn from thecoil l8. By operation of the valve 25 a minimum length of the coil ismaintained filled with superheated refrigerant vapor while the remainderof the coil contains liquid refrigerant or liquid refrigerant andsaturated vapor and is effective for dehumidifying the air passing overthe coil and for substantially reducing the sensible heat of the air.

It has been pointed out above that by operat-' ing only a portion of thecooling coil at low temperature while the remainder of the coil containssuperheated refrigerant vapor the humidity may be decreased withoutsubstantially decreasing the sensible heat of the air in the room. Thisfurther reduction of humidity is accomplished as has already been statedby arranging the room humidostat so that it will take over the operationof the refrigerating machine in the event that the humidity is still toohigh after the room thermostat is satisfied.

I, therefore, provide a second valve 6i arranged in parallel with thevalve 25 and provide a solenoid or motor-operated valve 63 in serieswith the valve 25 to cut out the valve 25 when desired. The secondrefrigerant controlling valve 6| is set to maintain a higher temperatureof the refrigerant vapor withdrawn from the coil l8 and therebytomaintain a greater length of the coil filled with superheatedrefrigerant vapor. Whenever the control of the refrigerating machine istaken over by the humidostat the valve 25 is cut out and the coolingcoil is supplied with refrigerant through the second valve 6|.

I have shown the second thermostatic controlling valve 6! connected inparallel with the valve 25 and having a thermostatic bulb 62 secured tothe cooling coil I 8 intermediate the ends thereof. It will readily beapparent that if the valves 25 and BI are both set to maintain the sametemperature of the coil at the places where their respectivethermostatic bulbs are attached then the valve 6| will maintain only asmall portion of the coil 58 at a low temperature, as compared with theportion operating at a low temperature under the control of the valve25. In series with the valve 25 is arranged the solenoid control valve63 which is biased by a spring 64 to its closed position, shown in thedrawing. The valve 63 is opened by energization of a coil 65 whichraises an armature 66 whenever the refrigerating machine is controlledin response to the theraiiaoso refrigerant to the coil i8 is controlledsolely by the valve 25. This is apparent since the operation of thevalve 25 will maintain a minimum temperature of the refrigerantwithdrawn from the coil i8 making it impossible for the valve 6! .ing aholding circuit for the coil it.

to be opened, because the temperature of the coil H3 at the point wherethe bulb 62 is connected cannot risesumciently to open the valve 8 l.

During the operation of the air conditioning system shown, should thehumidity of the room still be above the desired value after thethermostat 28 has been satisfied, the humidostat 29 will be in aposition to operate the relay 2% to shift the control of the refrigerantsupply for the coil l8 from valve 25 to valve Si by closing valve 63,and will also maintain the refrigerating machine in,.operation. When thehumidity is too high a movable member 12 of the humidostat 29 engages acontact i3 establishing a circuit from one side of the secondary 36 ofthe transformer through the connection iii, the arm 86 of relay 28a, aline it, a connection E5, the member 72, a contact l6 and a bimetallicstrip ll of the limit thermostat 3i and a connection 78 to a coil E9 ofrelay 29a and back to the other side of the secondary 36 through a lineM. This energizes the coil it, raises an armature 80 of the relay 29aand lifts the arm 68 and an arm ti, thereby breaking the circuit of thesolenoid t5 and clos- The holding circuit includes a connection 5i fromone side of the secondary 36 of the transformer, arm

.65, line it, arm 8i and a connection 32 to one side of the coil ill,and from the other side therearm W, the connection ti and line M to coil52' and thence to line 33 through the connection 55, thereby energizingcoil 52 and operating switch 30 to start the motor 2% of therefrigerating machine and supply refrigerant to the coil it through thevalve 6i. i

The operation under thetcontrol of the humidostat of the refrigeratingmachine, supplying refrigerant to the coil it through the valve 6i willthus maintain a higher temperature of the re frigerant withdrawn fromthe coil l8, thereby reducing the rate of sensible cooling of the air,but continuing the dehumidification of the air since a small portion ofthe coil Ill is maintained at a sufficiently low temperature for thispurpose. Further moisture will, therefore, be abstracted from the airwith less than normal decrease in the sensible heat of the air in theroom.

The operation of the refrigerating machine underthe control of thehumidostat will continue until the humidityhas been reduced to a desiredvalue or until the temperature of the air has reached a" minimumpermissible value consistent with comfort. Should the humidostat besatisfied the movable member 12 will engage a contact therebyshort-circuiting the coil 19 through connection l8, strip TI, movablemember 12 and a portion of line 43. The relay 29a will then drop out anddiscontinue operation of the motor 28 by opening switch 38.- Should thetemperature of the air in the room reach the minimumper- ,missibletemperature before the humidostat 29 is satisfied, the strip ill willengage a contact 86 and short-circuit the coil 19 through connection I8,strip Ill, and a connection 87,

thereby deenergizing the relay 29a and stop- .mostat, therefore, takesprecedence over the control in response to the humidostat.

In Fig. 2, I have shown a modification of my invention, in which Iutilize a pressure responslve valve 88 in parallel with..the valve 25 inorder tomaintain a greater length of coil l8 filled with superheatedvapor. The valve 88 is arranged to'open in response to a predeterminedlow pressurein the coil l8. This pressure is lower than the pressureobtaining in the coil when the refrigerating machine is supplyingrefrigerant through the valve 25. The valve 88, therefore,

remains closed as long as the valve 25 is inoperation. However, when thesolenoid valve 53 operates to cut ofi the valve 25 in response to theroom humidostat, the pressure in the coil it be- 1 comes lower and thevalve 88 operates to supply refrigerant to the coil. The supply ofrefrigerant through the valve 88 is restricted so that only a smallportion of the coil is maintained at a low temperature, due to thepresence of liquid refrigerant, while a greater portion is filled withsuperheated refrigerant vapor. It is readily apparent that thisarrangementof valves will operate in the same manner as that shown inFig. l. to maintain either one of two predetermined temperatures of therefrigerant withdrawn from the coil it.

While I have disclosed particular embodiments of my invention, variousmodifications will occur to those skilled'in the art and I do not,therefore, desire my invention to be limited to the construction shownand described, and' I intend in the appended claims to'cover allmodifications that do not depart from the spirit and scope of myinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A system for conditioning the air within an enclosure including acooling element, means for supplying cooling medium to said element andfor withdrawing cooling medium from said element, means including avalve and arranged to control the supply of cooling medium to saidcooling element for maintaining a predetermined substantiallyconstanttemperature of the cooling medium withdrawn from said element, meansincluding a second valve connected in parallel with said first valve andarranged to control the supply of cooling medium to said cooling elementfor maintaining a different substantially constant the humidity of theair within said enclosure'for shifting from one of said valves to theother the control of the supply of cooling medium to said coolingelement.

2. A system for conditioning the air within an enclosure including acooling element, means for supplying cooling medium to said element andfor withdrawing cooling medium from said elenient, means including avalve arranged to con trol the supply of cooling medium to said coolingelement for maintaining a predetermined substantially constanttemperature of the cooling medium withdrawn from said element, meansincluding a second valve connected in parallel with said first valve andarranged to control the supply of cooling medium to said cooling elementfor maintaining a different substantially constant temperature of thecooling medium withdrawn from said cooling element,

means for rendering said first valve only effec valve,-and meansresponsive to the humidity of the air within said enclosure for closingsaid third valve to shift to said second valve the control of the supplyof cooling medium to said cooling element. v

3. A system for conditioning the air within an enclosure including acooling coil, means for supplying liquid refrigerant to said coil andfor withdrawing vaporized refrigerant from said coil,

means including a valve arranged to control the supply of liquidrefrigerant to said coil for maintaining superheated the vaporizedrefrigerant in a predetermined length of said coil, means including asecond valve connected in parallel with said first valve and arranged tocontrol the supply of liquid refrigerant to said coil for maintainingsuperheated the vaporized refrigerant in a different predeterminedlength of said coil, means for rendering said first valve only effectiveto control the supply of liquid refrigerant to said coil during normaloperation of said system, means including a third valve for control lingthe supply of refrigerant to said first valve, and means responsive tothe humidity of the air within said enclosure for closing said thirdvalve to shift to said second valve the controlof the supply of liquidrefrigerant to said coil.

4; A system for conditioning the air within an enclosure including acooling coil, means for supplying liquid refrigerant to said coil andfor withdrawing vaporized refrigerant from said coil, said meansincluding a supply conduit having parallel branches, means including avalve in each of said branches for controlling the flow of liquidrefrigerant through said branches to said coil, means including atemperature responsive element associated with each of said valves formaintaining superheated the vaporized refrigerant in different lengthsof said 0011, one of said valves being operable to control the supply ofliquid refrigerant to said coil during normal operation of said system,and means responsive to the humidity of the air in said enclosure fortransferring to another one of said valves the control of the supply ofliquid refrigerant to said coil.

b. A system for conditioning the air within an enclosure including acooling coil, means for supplying liquid refrigerant to said coil andfor Withdrawing vaporized refrigerant from said coil, said meansincluding a supply conduit having two parallel branches, means includinga valve in each of said branches for controlling the supaiiaosa ply ofliquid refrigerant to said coil, means responsive to the temperature ofthe vaporized refrigerant near the outlet end of said coil for actuatingone of said valves, means dependent upon a predetermined low pressure ofthe refrigerant in said coil for actuating the second of said valves tocontrol the supply of liquid refrigerant to said coil, means forrendering only one of said valves effective at the same time to controlthe supply of refrigerant to said coil, and means dependent upon thehumidity of the air within said enclosure for selecting one ofsaidvalves for operation to control the supply of liquid refrigerant tosaid coil.

6. A system for conditioning the air within an enclosure including acooling coil, means for supplying liquid refrigerant to said coil andfor withdrawing vaporized refrigerant from said coil,

said means including a supply conduit having two parallel branches,means including a valve in each of said branches for controlling thesupply of liquid refrigerant to said coil, means responsive to thetemperature of vaporized refrigerant near the outlet end of said coilfor actuating the first of said valves, means, responsive to thetemperature of the vaporized refrigerant at a point intermediate theinlet and outlet ends of said coil for actuating the second of saidvalves, means for rendering said first valve only effective duringnormal operation of said system, means including a third valve forcontrolling the supply of liquid refrigerant to said first valve,

' sponsive to the temperature of vaporized refrigerant near the outletend of said coil for actuating the first of said valves, means dependentupon a predetermined low pressure of the refrigerant in said coil foractuating the second of said valves to control the supply ofliquidrefrigerant to said coil, means for rendering said first valveonly effective during normal operation of said system, means including athird valve for controlling the supply of liquid refrigerant to saidfirst valve, and means responsive to the humid= ity of the air in saidenclosure for closing said third valve to transfer from said first valveto said second valve the control of the supply of liquid refrigerant tosaid coil.

8. A system for conditioning the air within an enclosure including acooling element, means for supplying cooling medium to said element andfor withdrawing cooling medium from said element, means including avalve arranged to control the supply of cooling'medium to said coolingelement for maintaining a predetermined substantially constanttemperature of the cooling medium withdrawn from said element, saidcooling medium supplying means including a conduit having a portioncomprising 'two branches arranged in parallel, means includinga secondvalve connected in one of said parallel branches and arranged to controlthe supply of cooling medium to said cooling element for main- 2,1 iacso& within said enclosure for operating said third valve to transfer thecontrol of the supply of cooling medium from one of said supplycontrolling means to the other.

9. A systemfor conditioning the air within an enclosure including acooling element, means for v supplying cooling medium to said elementand for withdrawing cooling medium from said element, said coolingmedium supplying means including a conduit having a portion comprisingtwobranches arranged in parallel, means including a valve arranged insaid conduit and having a thermostatic control member arranged on said.cooling element for controlling the supply of cooling medium to saidcooling element, means including a second valve connected in one of saidparallel branches and having a thermostatic control member on saidcooling element for controlling the supply of cooling medium to saidcooling element, means including a third valve arranged in the other ofsaid parallel branches for rendering only one of said supply controllingmeans efiective at the same time, and means responsive to the humidityof the air within said enclosure for, operating said third valve totrans fer the control of the supply of cooling medium from one of saidsupply controlling means to the other.

DAVID W. MCLENEGAN.

DISCLAIMER 2,112,039.Damd W. McLenegan, Caldwell, N. J. AIR CONDITIONINGSYSTEM.

Patent dated March 22, 1938. Disclaimer filed July 27, 1940, by theassignee, General Electric Company.

Hereby enters this disclaimer of Fig. 2 of the drawing of said patentand of that part of the specification of said patent appearing in lines21 to 46 inclusive in the second column on page 3 thereof, and herebyenters disclaimer of claims 5 and 7 of said patent.

[Ojficial Gazette September8, 1940.]

